Filter.



H. W. COWAN.

FILTER.

APPLICATION FILED MAR. 26. I9I4. 4 ,204,414.' Patented Nov. 14., 1916.

WI NISES; INV NTOR.

v l BY M J1 ,5% I w ,704W

A TTORNE vis/ STARS faeilifil 'HENRY WARRINGTON CGVAN, OF TORONTO,ONTARIO, CANADA.

FILTER.

Application filed March 26, 1914.

2 o all whom t may concern ie it known that i, HENRY VARRINGTON Contax,a subject of the King of Great Britain, and a resident of rfoionto,county of 'orlr, and Province of Ontario, Canada, have invented a newand useful Improvenient in ifiiters, of which the .following is aspecification.

My invention relates to filters and specifieahy appertains to waterfilters of the type in which water is allowed to flow through, or isforced, or drawn through a granular filter bed composed of sand,charcoal, crushed quartz, or other suitable material, which retains theimpurities in water.

it is well known that, as a filter bed becomes dirty, a greater waterpressure is required thereon to maintain the same rate of flow of waterthrough the filter. in the type of filter which is open to theatmosphere the pressure on the filter bed is supplied by a down drafttube from the filter, on which a controller is placed to maintain. aconstant rate of flow of water. in this way the pressure under thefilter bed is reduced to impart an excess pressure on the top of thefilter bed, the system being knownas the negative head process. Thissystem tends to create a vacuum in the filter' bed below the surface andthus tends to draw air from the water, which lodges in the filter bedand impedes the passage of water through the filter.

`When the granular .filter bed becomes dirty it is customary to passfiltered water back through the filter bed at the same time agitatingthe bed by means of compressed air or a mechanical device. The dirt thusloosened is removed by the wash water fiowing into a drain at a heightabove the filter bed high enough to prevent the filter material beingwashed out and yetlow enough to allow the dirt to be washed away. lyincreasing the height of water above the filter bed as the bed becomesdirty the same effect can be secured as that given by the down drafttube in negative head process without Ahe disadvantages accruing fromreleasing air in the filter bed. this height of water above the filterbed va ries with the pressure required, dependent upon the clear ordirty condition of the filter bed and at some times may require to beseveral feet. It will thus be seen that when the filter bed requirescleaning this added quantity of water above the height at whichSpecification of Letters latent.

it will be noted thatv Patented Nov. ist., ifif.

Serial No. 827,378,

i wash water flows out will have to be run fl nlil the level of thewater upon the l l reaches the point at which the Other objects of myinvention comprise the novel methods of construction and interrelatiouof parts as shown in the drawing which :.iccompanies and forms a part ofthis specification.

Referring now to the drawing which illustrates a diagrammatic sectionalview of impro-vcd filter, the pipe 3l delivers unfiltered or raw waterto the unfiltered water chamber and Si, from which the water passesthrough the granular bed 35, thence through a perforated fioor platecl2, through a bed of secondari7 or coarse filtering material il tocollecting pipes and thence to a filtered water pipe 3? and finally tothe filtered water chamber 3 the proper valves being supplied as shownto control the passage of the water to, through and from the filter.

In my invention I contract or restrict the plan area of a portion of theunfiltered water chamber by a novei construction, as shown, in order toreduce the volume of water above the filter bed without decreasing theheight of the water above the bed that the pressure per square inch oflthe water on the filter bed shall remain undisturbed. rlhis container 32of relatively small. plan area in comparison to the area of the filterbed allows the water to rise to the level of' the incoming raw waterpipe 31 and to thus impart sufiicient pressure upon the filter bed toinsure the proper action of the filter. By this novel construction I amable to produce the same pressure upon the filter bed as that necessaryin positive head filters but with considerably less volume of fater thanhas hitherto been necessary and consequently when the water above thedrain pipe 30 is run off preparatory to the operation of washing thefilter the quantity of water wasted is very much smaller in my improvedfili??? than with filters previously known, in fact, there is so littlewaste water in my lter that the positive head process may economicallybe employed, and the positive head process is extremely desirable inthat it prevents in a very large degree the formation of air in thefilter bed which tends to reduce the capacity of the filter.

lVhile l have shown one embodiment of my invention l do not wish to belimited thereto and it should be fully understood that l may alter thedetails of my invention without narrowing the scope of the invention.

laving thus described my invention what I claim as new and desire tosecure by United States Letters Patent is as follows:

l. In a filter, an unfiltered water chamber, a filtered water chamberand a filter bed therebetween, an overfiow pipe communr eating with saidunfiltered water chamber, said chamber having a` plan area substantiallyequal to that of said filter bed below said overow pipe, and saidchamber having a plan area considerably less than said filter bed abovesaid overflow pipe.

2. ln an atmospheric filter, an unfiltered water chamber, a filteredwater chamber and a filter bed therebetween, an outlet pipecoinmunicating with said unfiltered water chain` ber belowv the waterlevel therein, said unfiltered water chamber having a plan areasubstantially equal to that of' said filter bed below said outlet pipe,and said chamber having a plan area considerably less than said filterbed above said outlet pipe.

3. In an atmospheric filter, an unfiltered water chamber, a filteredwater chamber, and a filter bed therebetween, an outlet pipecommunicating with said unfiltered water chamber at substantially thelevel that wash water rises in said chamber during the wash-v ing outprocess, said chamber having a plan area substantially equal'to that ofsaid filter bed below said outlet pipe, and saidV chamber having a planarea considerably less than said filter' bed above said outlet pipe.

Signed by me at rloronto, county of York and Province of Ontario,Canada, in the presence of two witnesses.

HENRY WARRINGTON COVVAN.

l/Vitnesses JAMES M. SINCLAIR, BETA DARCH.

Copies of this patent may be obtained for ve cents each, by addressingthe "Commissioner of Patents,

Washington, D. G.

